1. Field of the Invention
The present invention relates to a machine room-less elevator having no machine room disposed above an elevator shaft provided in a building.
2. Description of the Related Art
Various machine room-less elevators having no machine room disposed above an elevator shaft have been developed and proposed for efficiently utilizing spaces in buildings and for observing regulations regarding the right to sunlight.
For example, in a conventional machine room-less elevator shown in FIGS. 7 and 8, a driving unit 3 is fixed to a top wall surface 2 of the elevator shaft in which a cage 1 is adapted to move vertically, and a hoist cable 5 including a plurality of small diameter ropes is wound around a traction sheave 4 rotationally driven by the driving unit 3.
A portion of the hoist cable 5 extending downwardly from the traction sheave 4 toward the cage 1 comprises a portion 5a extending downwardly along a left side wall 1a of the cage 1, a portion 5b horizontally extending between a pair of right and left cage-side sheaves 1c and 1b rotatably supported by a lower part of the cage 1, and a portion 5c extending upwardly along a right sidewall 1d of the cage 1 and fixed to a hitching device 6 provided in the top space of the elevator shaft. Thus, an one end of the hoist cable 5 suspends the cage 1 in a two-to-one roping arrangement.
Similarly, a portion of the hoist cable 5 extending downwardly from the traction sheave 4 toward a counterweight 7 comprises a portion extending downwardly along the side-wall 2 of the elevator shaft, a portion wound around a counterweight-side sheave 7a rotatably supported by an upper part of the counterweight 7, and a portion extending upwardly from the counterweight-side sheave 7a and fixed to a hitching device (not shown) provided in the top space above the elevator shaft. Thus, another end of the hoist cable 5 suspends the counterweight 7 in a two-to-one roping arrangement.
In a conventional machine room-less elevator shown in FIGS. 7 and 8, since the cage-side sheaves 1b and 1c are provided under the cage, the depth of a pit provided in the bottom of the elevator shaft becomes deep inevitably.
In addition, since the hoist cable 5 is extending vertically along the right and left side walls 1a and 1d of the cage 1, the width “L” of the elevator shaft in the right-to-left direction becomes large to secure enough width “W1” of the cage 1 in the right-and-left direction (the door opening/closing direction).
In other words, provided that the dimension “L” of the elevator shaft cross section in the right-to-left direction is set at a specified value, the dimension “W1” in the right-to-left direction of the cage 1 become small inevitably.
In addition, the maintenance of the driving unit 3, the traction sheave 4 and a control device 8 fixed to the top side wall of the elevator shaft must be performed by an operator riding on the cage 1 stopped in the highest position of the elevator shaft.
Contrary to this, the maintenance of the cage-side sheaves 1b and 1c must be performed in the pit during the time when cage 1 is stopped in the lowest position of the elevator shaft.
Accordingly, in the above-mentioned conventional machine room-less elevator, the maintenance work cannot be efficiently performed.